Solenoid valve

ABSTRACT

A solenoid coil assembly for a solenoid valve includes an electrical coil wound about a valve armature to develop a magnetic field for actuating the armature responsive to an electrical current passing through the coil. A case surrounds the coil. The case has opposite end walls and a top wall, a bottom wall and opposite side walls connected between the end walls. A pair of electrical connectors are connected to opposite ends of the coil and extend outwardly from the top wall. A metal yoke has opposite end walls connected by a top wall and a bottom wall. The yoke is received on the case with their respective end walls, top walls and bottom walls in alignment.

FIELD OF THE INVENTION

This invention relates generally to solenoid valves and, moreparticularly, to an improved solenoid coil assembly therefor.

BACKGROUND OF THE INVENTION

Solenoid valves are suitable for a wide variety of applications and maycomprise cartridge valves such as, for example, both direct acting andpilot operated on/off poppet valves.

In one form of a pilot operated poppet valve, a spring acts on anarmature to selectively open or close a pilot valve in the center of apoppet depending upon whether the valve is of a normally open ornormally closed type. The armature is movable within a solenoid, whichincludes an energizable coil. When the solenoid coil is energized, thepilot valve is actuated.

A typical prior solenoid coil assembly includes a coil wound on a bobbinand surrounded by a yoke made of a ferromagnetic material. As is wellknown, the yoke operates to enhance the magnetic conduction or flexdensity to improve operation. This assembly is encapsulated in a plasticcase to retain the same in assembled relation and provide an outerhousing. A ferromagnetic washer may also be included in the assemblybetween one end wall of the case and the yoke. The washer serves thesame purpose as the of the housing for connecting to a source of power.One for the plastic case to crack. Specifically, owing to thermalcharacteristics, the metal yoke expands and contracts at a differentrate from the plastic case causing thermal shock which results incracking of the plastic.

One known solution of the thermal shock problem involves placing theyoke outside of the plastic case. A prior known solenoid assemblyincludes a plastic case encapsulating a coil and having a top wall, abottom wall and opposite side walls. One of the end walls has anencapsulated ferromagnetic washer. The top wall is provided with ahousing for electrical connectors which are connected to the coil. Ametal yoke which is rectangular in configuration has opposite end wallsconnected by opposite side walls. The yoke is mounted on the plasticcasing with its respective end walls and side walls in alignment withthe end walls and side walls of the case.

Various valve packages are available which utilize cartridge valves toprovide segments of hydraulic circuits ranging from single valves tomulti-function manifolds. Such packages can be preassembled and testedfor installation in a hydraulic circuit. Particularly, assemblies knownas polyhydrons have been utilized to satisfy such requirements. Thepolyhydron provides interconnections between cartridge valves by drilledholes, thereby eliminating pipe work, expensive fittings and reducingthe potential for leakage. Because the valves are mounted closertogether pressure losses are reduced and hydraulic circuits become moreefficient. The elimination of pipe work results in a neaterinstallation, saving assembly time and wait. Because the package isinstalled as one complete unit the possibility of introducingcontamination of the circuit during assembly is also reduced.

With a polyhydron type valve package it may be necessary to closelymount several cartridge valves. However, access must be provided forelectrical connections to the valve solenoids. Thus, with theabove-described cartridge valve, including an outer yoke, access must beprovided to the top wall mounted housing Further, the outer yoke sidewalls require that adjacent cartridge valves must be further spaced fromone another to allow room for the same, resulting in an increase in thesize, and thus weight, of the polyhydron. Also, this type of coil isnon-symmetrical, requiring that it be installed on a valve with the endwall having the washer on the side opposite the valve. The reversedinstallation leads to loss of solenoid power.

The present invention is directed to overcoming one or more of theproblems discussed above.

SUMMARY OF THE INVENTION

In accordance with the invention, a solenoid coil assembly includes anouter yoke which requires less available space.

Broadly, there is disclosed herein a solenoid comprising a bobbin havinga through opening defining a central axis, and an electrical coil woundabout the bobbin coaxial with the axis to develop a magnetic field inthe opening responsive to an electrical current passing through thecoil. A case surrounds the coil. The case has opposite end wallsperpendicular to the axis and a top wall, a bottom wall and oppositeside walls connected between the end walls. A pair of electricalconnectors are connected to the opposite ends of the coil and extendoutwardly from the top wall. A metal yoke has opposite end wallsconnected by a top wall and a bottom wall. The yoke is received on thecase with their respective end walls, top walls and bottom walls inalignment.

It is a feature of the invention that the yoke bottom wall is the samesize as the yoke top wall.

It is another feature of the invention that the yoke end walls includeopenings aligned with the bobbin through opening.

It is a further feature of the invention that the case comprises aconnector housing disposed above the case top wall and carrying theelectrical connectors.

It is still a further feature of the invention that a portion of theconnector housing is spaced from the case top wall to define a space andthe yoke top wall is received in said space.

It is another feature of the invention that the yoke dimensions aredetermined so as to eliminate the end wall washer. As a result, the coilis symmetrical, making it convenient to use.

It is an additional object of the invention to provide a solenoid coilassembly for a solenoid valve including a valve and an armature moveablealong an axis for actuating the valve. An electrical coil is wound aboutthe armature coaxial with the axis to develop a magnetic field foractuating the armature responsive to an electrical current passingthrough the coil. A case surrounds the coil. The case has opposite endwalls perpendicular to the axis and a top wall, bottom wall and oppositeside walls connected between the end walls. A pair of electricalconnectors are connected to opposite ends of the coil and extendoutwardly from the top wall. A metal yoke has opposite end wallsconnected by a top wall and a bottom wall. The yoke is received on thecase with their respective end walls, top walls and bottom walls inalignment.

Further features and advantages of the invention will readily beapparent from the specification and from the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic section of a cartridge valve including asolenoid coil assembly embodying the invention;

FIG. 2 is a side elevation, with parts cut away for clarity, of thesolenoid coil assembly of the valve of FIG. 1;

FIG. 3 is a section taken along the line 3--3 of FIG. 2;

FIG. 4 is an opposite side elevation view taken along the line 4--4 ofFIG. 3; and

FIG. 5 is a plan view taken along the line 5--5 of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, a cartridge valve 10 includes a solenoid coilassembly 12 according to the invention for operating a valve assembly14. The illustrated cartridge valve 10 comprises a normally closed pilotoperated poppet type valve.

In accordance with the broad concepts of the invention, the solenoidcoil assembly 12 can be used with any cartridge type valve, as will beobvious to those skilled in the art.

The poppet valve assembly 14 includes an adapter 16 which receives aseat member 18. The seat member 18 may be received in the adapter 16 inany known manner. The seat member 18 is provided with suitable means forbeing received in a fluid port, such as, for example, a drilled bore ina polyhydron or manifold.

The seat member 18 is provided with a side opening 20 which opensradially inwardly into a valve chamber 22. An end opening 24 opensaxially from the valve chamber 22 and is normally closed by a valvemember, or poppet, 26 seating on an annular seat 28 of the seat member18 at an inner end of the end opening 24.

The valve member 26 comprises a poppet valve having a seating portion 30engaging the valve seat 28 and provided with an axial bore 32 which isnormally closed by a pilot valve 34 received in a cylindrical recess 36of the valve member 26. The pilot valve 34 provides fluid communicationbetween a transfer chamber 38 and a pilot valve chamber 40.

The pilot valve 34 includes an inner end 41 secured to a solenoidarmature, or plunger, 42. In a normally closed arrangement of the poppetvalve assembly 14, the plunger 42 is biased outwardly by a helical coilspring 44 acting between an inner end portion 46 of the plunger 42 and aplug 48.

In operation, when system pressure is applied to the side port opening20, it is kept closed by the coil spring 44 acting on the plunger innerend 46 closing off the pilot valve 34 in the center of the poppet 26.When the solenoid coil assembly 12 is energized, as discussed below, thearmature 42 is pulled away from the bore 32 allowing pilot flow throughan orifice 50 in the poppet 26 between the valve chamber 22 and thepilot valve chamber 40. This pilot flow through the orifice 50 causes apressure imbalance across the poppet 26 which opens the same to allowopening 24.

With reference also to FIGS. 2-5, the solenoid coil assembly 12 includesa coil sub-assembly 52, an outer shell 54, and a screw 56, see FIG. 2.

With specific reference to FIG. 1, the coil sub-assembly 52 includes abobbin 58 having a central through opening 60 defining an axisrepresented by a line 62. A coil 64 is wound about the bobbin 58. Thecoil 64 comprises a multi-turn winding with the number of turns and sizeof the wire determined according to the voltage and power requirements,as is well known. The ends of the coil 64 are connected to electricalconnectors, such as male connectors 66. As is well known, application ofpower across the connectors 66 causes current flow through the coil 64to produce a magnetic field within the bobbin through opening 60. Thismagnetic field acts on the plunger, or armature, 42, shown in FIG. 1 toactuate the cartridge valve 10.

The coil sub-assembly 52 is encased in a plastic case 68. Specifically,the case 68 in the illustrated embodiment comprises a molded plasticcase which encapsulates the coil 64 and the bobbin 60. The case 68includes opposite end walls 70 and 72. The end walls 70 and 72 areinterconnected by a top wall 74 and opposite, bottom walls 76, and alsoby opposite and parallel side walls 78 and 80. The side walls 78 and 80interconnect the top wall 74 and the bottom wall 76 to provide agenerally square configuration. The case walls are provided with aplurality of axial ridges 82.

The case 68 includes a connector housing 84 disposed above the top wall74. The connector housing 84 is L-shaped and includes a lower portion 86connected to the top wall 74 and having an outer wall 88 flush with theside wall 80. A housing upper portion 90 houses and supports theconnectors 66 and is spaced outwardly from the top wall 74 to define aspace 92 therebetween. The space 92 is laterally open from the coilassembly side wall 78 to the connector housing lower portion 86. Anaperture 93 is provided through the top of the housing upper portion 90for receiving the ground screw 56, see FIG. 3.

The outer shell 54 comprises a yoke made of ferromagnetic material. Theyoke 54 includes opposite, parallel end walls 94 and 96 connected by atop wall 98 and an opposite, parallel bottom wall 100. The yoke 54 maybe of single piece construction, or may have separate walls which aresecured together by any known means, as necessary, or desired.

The yoke end walls 94 and 96 are generally square in the illustratedembodiment corresponding to the size of the case end walls 70 and 72,and include respective central circular openings 102 and 104. Theopenings 102 and 104 are identical in diameter and, in fact, aresubstantially identical in diameter to the bobbin through opening 60.The top wall 98 and bottom wall 100 are generally rectangular and have alength slightly greater than that of the case top and bottom walls 74and 76, but having a narrower width. Specifically, the yoke dimensionsare determined with the consideration of eliminating the need for an endwall washer, thus providing a symmetrical coil. The yoke bottom wall 10is centrally positioned relative to its end walls 94 and 96, while thetop wall 98 is offset from center and, in fact, has one edge slugh withthe side edge of the yoke ends walls 94 and 96. The width of the topwall 98 is less than the space 92 described above between the case sidewall 78 and the connector housing lower portion 86.

The yoke 54 is mounted to the coil sub-assembly 52 by sliding it intoposition so that the yoke end walls 94 and 96 are in alignment with thecase end walls 70 and 72 and their respective openings 102 and 104 inalignment with the bobbin central opening 60. Similarly, the yoke topand bottom walls 98 and 100 are aligned with the case top and bottomwalls 74 and 76, respectively. Specifically, the yoke bottom wall 100 iscentered relative to the case bottom wall 76. The yoke top wall 98 isreceived in the space 92 between the case top wall 74 and the enclosurehousing 84.

As is well known, the yoke 54 carries the magnetic field developed inthe coil 64, see FIG. 1, and is effective to increase the flux density,or magnetic induction, developed thereby.

By supporting the yoke 54 outwardly of the case 70, the structuralintegrity of the case is enhanced. Specifically, thermal expansion ofthe yoke 54 will not cause cracking of the plastic case 70. Further,since the yoke 54 does not extend beyond the case side walls 78 and 80,the valve 10 may be closely mounted to adjacent valves on either side.

Thus, the invention broadly comprehends a solenoid coil assemblyincluding an outer yoke which permits side-by-side installation toadjacent solenoids in close proximity.

What is claimed is:
 1. In a solenoid valve including a valve and anarmature movable along an axis for actuating said valve, a solenoid coilassembly comprising:an electrical coil wound about said armature coaxialwith said axis to develop a magnetic field for actuating said armatureresponsive to an electrical current passing through said coil; an outercase surrounding said coil, said case having opposite end wallsperpendicular to said axis and a top wall, a bottom wall and oppositesidewalls connected between said end walls; a pair of electricalconnectors connected to opposite ends of said coil and extendingoutwardly from said top wall; and a metal yoke having opposite end wallsconnected by a top wall and a bottom wall, said yoke being removablyreceived on said case with the respective end walls, top walls andbottom walls in alignment.
 2. The solenoid coil assembly of claim 1wherein said yoke top wall is the same size as said yoke bottom wall. 3.The solenoid coil assembly of claim 1 wherein said yoke end wallsinclude openings for receiving said plunger.
 4. The solenoid coilassembly of claim 3 wherein said openings are of the same diameter toprovide a symmetrical coil.
 5. The solenoid coil assembly of claim 1wherein said case further comprises a connector housing disposed abovesaid case top wall and carrying said electrical connectors.
 6. Thesolenoid coil assembly of claim 5 wherein a portion of said connectorhousing is spaced from said case top wall to define a space and saidyoke top wall is received in said space.
 7. The solenoid coil assemblyof claim 1 wherein said case comprises a plastic case.
 8. The solenoidcoil assembly of claim 7 wherein said coil is encapsulated in said case.